/Engine/Source/Runtime/Engine/Classes/PhysicsEngine/PhysicsAsset.h
Set whether or not a primitive volume contributes to the mass of the object.
void SetPrimitiveContributeToMass ( int32 BodyIndex, [EAggCollisionShape::Type](API\Runtime\Engine\PhysicsEngine\EAggCollisionShape__Type) PrimitiveType, int32 PrimitiveIndex, bool bContributesToMass )